. . was heavily used for "medical" purposes, particularly as a laxitive, but I think it went out of style in the '50s.

The Castor Bean plant is very common through much of the U.S. and grows well wild. The beans are very toxic but the toxins are not disolved in the oil. Fortunately, the attractive beans are also hard and indigestible, so kids that swallow them generally just pass them through.

I have fond memories of the smell of "Castrol R" racing oil, which was Castor Oil based and provided better lubrication under high stress than the mineral oils of the day (and perhaps even today). It was a bit pricy though, and had to be flushed and changed frequently. Castrol is still a major motor oil company, but I don't know if they still make the "R" product.